As disclosed in Unexamined Japanese Patent Application KOKAI Publication No. H10-90678 and Unexamined Japanese Patent Application KOKAI Publication No. 2001-290445, a liquid crystal display device in which two liquid crystal display elements are disposed back to back with their display surfaces facing the opposite directions from each other, and a surface light source for emitting a light toward both the liquid crystal display elements is disposed between them, is known as a both surface display type liquid crystal display device to be used in a portable apparatus such as a portable phone, which has a display function on both surfaces of its case.
However, using two liquid crystal display elements as described above costs high, and both surface display with the use of one liquid crystal display element is desired.
As a liquid crystal display device for both surface display using one liquid crystal display element, there is proposed a liquid crystal display device in which the screen area of a liquid crystal display element is divided into a first screen portion and a second screen portion so that an image to be viewed from the front is displayed by the first screen portion and an image to be viewed from the back is displayed by the second screen portion, as disclosed in Unexamined Japanese Patent Application KOKAI Publication No. 2000-193946 and Unexamined Japanese Patent Application KOKAI Publication No. 2001-305525.
However, in a both surface display type liquid crystal display device having the screen area of its liquid crystal display element divided into a first and a second screen portions, the entire display area of the liquid crystal display element has a size corresponding to the size of the display screen for the front plus the size of the display screen for the back which are arranged side by side. Therefore, the occupation area of this liquid crystal display device is much larger than that of a display screen for either front or back display. Accordingly, this liquid crystal display device can not be used in a portable apparatus such as a portable phone, in which the mount space for a liquid crystal display device is limited.